Young, George, jr, Baxter, Hubert Eugene, joint author · New York, Macmillan · leaf 153
a. 134 DESCRIPTIVE GEOMETRY [VII, § 121 121. The Ellipse. An ellipse is generated by a point whichmoves so that its distance from a fixed point bears to its dis-tance from a fixed line a constant ratio less than unity. (Seealso § 112.) For typical form and nomenclature for the ellipsesee Fig. 130.… … nf=cv. kf: kl;: df: dp:: df: dp:: vf: vo < i. = eccentricita-df+df= vf+vf = vv.df and df= focal distances of d.Fig. 130 djJdp are equal to the eccentricity of the curve. Also c//ctis the same ratio. The ellipse may also be defined as a curve generated by apoint which moves so that the sum of its…
Geometry, Descriptive
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